1. Field of the Invention
This invention relates to an improvement in the construction of a mower unit for discharging grass clippings.
2. Description of the Related Art
In a conventional mower unit, as shown in FIGS. 14 and 15, an endless rotational belt 29 has a moving path including a straight path portion L1 between pulleys 26 and 28. A deck plate 17 defines an upper surface 40a of a grass discharge passage 40 inclined upward and rearward from adjacent a position over the straight path portion L1. The rear end of the upper surface 40a is located above the endless rotational belt 29. Thus, the upper surface 40a of grass discharge passage 40 defines a ceiling wall 41 not interfering with the rear moving path portion L1. Grass clippings cut by rotary blades 16 are carried along the grass discharge passage 40 by airflows generated by rotation of the rotary blades 16, to be discharged in batches from a grass discharge opening 20 at the rear end of the grass discharge passage 40.
It may be necessary for the grass clippings discharged in batches from the grass discharge opening 20 to be blown to a higher level than the discharge opening 20. In this case, the discharge opening 20 should preferably have an upper edge 20a located at an elevated level. In the above construction, the upper surface 40a of grass discharge passage 40 must extend with a steep gradient in order to raise the upper edge 20a of discharge opening 20 while maintaining the ceiling wall 41 of grass discharge passage 40 out of interference with the endless rotational belt 29. However, the steeper the upper surface 40a of grass discharge passage 40 is, the greater is the chance of airflows stalling while moving along the upper surface 40a. Especially, damp grass clippings carried by the airflows through the grass discharge passage 40 tend to adhere to the upper surface 40a of the discharge passage 40 to impair transporting efficiency.
The object of this invention is to provide a mower unit which overcomes the disadvantage noted above, and a grass cutting machine having such a mower unit.
The above object is fulfilled, according to this invention, by a mower unit comprising a first blade rotatable clockwise in plan view, a first pulley rotatable with the first blade to drive the first blade, a second blade disposed rightward from the first blade and rotatable counterclockwise, the second blade being level with or displaced from the first blade in a fore and aft direction, a second pulley rotatable with the second blade to drive the second blade, an endless rotational belt for transmitting drive at least between the first pulley and the second pulley, and a grass discharge passage disposed between rotary shafts of the first pulley and second pulley and having an inclined upper surface. A portion of the endless rotational belt extending between the first pulley and the second pulley is offset forwardly, in the fore and aft direction, of a phantom line extending between the rotary shafts of the first pulley and second pulley. The upper surface of the grass discharge passage begins to incline in a position forwardly of the phantom line.
In the above construction, the endless rotational belt is offset forward, and the upper surface of the grass discharge passage has a ceiling wall thereof which may be inclined from a forward position within a range not interfering with the endless rotational belt.
Thus, in an embodiment of this invention, the upper surface of the grass discharge passage has a rising end located more forwardly than in the conventional mower unit. The rear end of the grass discharge passage is located at a correspondingly elevated plane even where the upper surface extends with the same gradient as in the prior art.
The upper surface of the grass discharge passage may be less steep than in the conventional mower unit. It is also possible to elevate the rear end of the upper surface of the grass discharge passage to a higher level than in the conventional mower unit.
Consequently, while avoiding lowering of the efficiency of transporting grass clippings, the rear end of the upper surface of the upwardly inclined grass discharge passage may be elevated to an increased height.